FOSSILISED DINOSAUR eggs believed to be some 190 million years old have been found in a South African national park.
Palaeontologists have discovered 10 nesting sites, together with the footprints of hatched fledglings, in a cliff face in the Golden Gate Highlands National Park in the foothills of the Maluti Mountains of the north eastern Free State.
The nests are believed to have been made in the early Jurassic period by the herbivore dinosaur, the Massospondylus carinatus.
Each of the 10 nesting sites contains several clutches of eggs, and they are found at various levels in the cliff face. It is believed that some of the eggs also contain fossilised embryos.
Massospondylusgrew to four to six metres long as adults, say the researchers, but their eggs are only six centimetres in diameter.
According to the research published this month in the journal, Proceedings of the National Academy of Sciences, the highly organised nature of the nests suggests the mothers may have arranged their eggs carefully after laying them.
“Even though the fossil record of dinosaurs is extensive, we actually have very little fossil information about their reproductive biology, particularly for early dinosaurs,” said Dr David Evans, curator of vertebrate palaeontology at the Royal Ontario Museum in Canada.
The fossilised tracks left behind by the dinosaurs show that hatchlings stayed in the nest until they doubled in size, and that the young Massospondylus walked on four legs while young. The animal then likely stood upright on two legs as an adult.
The nests were found near the same location in the foothills of the Drakensberg Mountains in the Free State province where scientists previously found the oldest known dinosaur embryo in 2005. It was this earlier find that prompted them to return and continue their search.
“The eggs, embryos and nests come from the rocks of a nearly vertical road cut only 25 metres long,” said palaeontologist Robert Reisz, a professor of biology at University of Toronto Mississauga.
“Even so, we found 10 nests, suggesting that there are a lot more in the cliff, still covered by tonnes of rock. We predict that many more nests will be eroded out in time as natural weathering processes continue.”
The excavation work was led by Canadian and South African researchers, and they say their findings suggest the mothers were caring and returned repeatedly to the site. This is the oldest known evidence of such behaviour among dinosaurs.